甲基转移酶SETD3在RNA可变剪接中的作用

RNA可变剪接是真核生物实现蛋白质种类多样性的一种方式，这一事件在调控细胞增殖、细胞分化以及器官发育等多种生命过程中发挥重要作用。RNA剪接事件受到多重因素的精细调控。已有研究表明，不同种类的RNA剪接蛋白的翻译后修饰也参与了RNA剪接进程。申请人长期从事SETD3蛋白的研究工作。我们的部分研究结果表明，甲基转移酶SETD3可以与多个RNA剪接蛋白互作，细胞内敲低SETD3会改变RNA可变剪接进程，特别是促进外显子跳跃的发生。因此，本申请书将通过生物化学、细胞生物学和高通量测序方法，深入探究SETD3如何影响RNA可变剪接进程；明确其甲基转移酶活性在该事件中的作用；最终拟揭示SETD3调控RNA可变剪接的生物学意义。鉴于SETD3最近被鉴定为组氨酸甲基转移酶，因此本项目的开展不仅将阐释SETD3蛋白调控RNA可变剪接的分子机制，同时可能为扩展组氨酸甲基化修饰底物及功能的研究奠定基础。

Pre-mRNA alternative splicing is a major source for protein diversity in higher eukaryotes. Alternative splicing plays critical roles in cell proliferation, differentiation, and development. RNA splicing is predominantly regulated by many aspects, including RNA sequence elements, diverse splicing factors and chromatin structure. Increasing evidence indicate that post-translational modifications of splicing-associated factors are also involved in this process. This applicant has been studying the roles and regulation of SETD3 protein for several years. The preliminary data suggest that the methyltransferase SETD3 associates with many RNA splicing-related proteins by mass spectrometry analysis. Moreover, knockdown of SETD3 in HeLa cells led to alterations of many RNA alternative splicing events, mainly to promoting exon skipping. In this proposal, using biochemical, cell biology and genome-wide sequencing techniques, we will explore how SETD3 regulates RNA splicing events, and determine if the enzymatic activity of SETD3 is related to splicing. Eventually, we attempt to unveil the biological relevance of SETD3-regulated RNA splicing. Since SETD3 is a bona fide histidine methyltransferase that was reported very recently, this project may not only decipher the molecular basis of how SETD3 regulates RNA splicing, but pave an avenue for studying the new substrate(s) on histidine methylation by SETD3 as well as its related biological functions.